The present invention relates to a semiconductor light emitting device and a method for manufacturing the same, and more particularly, to a semiconductor light emitting device having a light scattering-deflecting layer and a method for manufacturing the same.
Semiconductor light emitting devices, such as light emitting diodes (LED), are formed by using semiconductor materials. The semiconductor light emitting devices are one kind of minute solid-state light sources that can transform electrical energy into light energy. The semiconductor light emitting devices not only have the features of small volume, long life, low driving voltage, rapid response speed, and shockproof, but also can meet the needs of various application apparatuses of lightness, thinness, and miniaturization, thus having become very popular electric products in daily life.
Referring to FIG. 1, FIG. 1 illustrates a cross-sectional view of a conventional semiconductor light emitting device. In the formation of the semiconductor light emitting device, a semiconductor layer 102 is first formed on a substrate 100 that is transparent by using a deposition method, and a n-type semiconductor layer 104 is formed on the semiconductor layer 102 by using an epitaxy method. Then, a luminescent structure 106 is formed on the n-type semiconductor layer 104 by using an epitaxy method similarly. A p-type semiconductor layer 108 is formed on the luminescent structure 106 similarly by using an epitaxy method, wherein the n-type semiconductor layer 104, the luminescent structure 106, and the p-type semiconductor layer 108 constitute a semiconductor light emitting structure.
Next, a definition step is performed by using a photolithograph technique and an etching technique to remove a portion of the luminescent structure 106 and a portion of the p-type semiconductor layer 108, so as to expose a portion of the n-type semiconductor layer 104. Thereafter, an electrode 110 and an electrode 112 are formed respectively on the p-type semiconductor layer 108 and on the n-type semiconductor layer 104 by using a thermal evaporation method, an e-beam evaporation method, or an ion sputtering method, so as to complete the semiconductor light emitting device.
An objective of the present invention is to provide a semiconductor light emitting device, such as a light emitting diode, the semiconductor light emitting device comprising a semiconductor layer having a scraggly surface and a light scattering-deflecting layer of which a refractive index is different from that of the semiconductor layer. Therefore, light is deflected while the light enters the semiconductor layer from the light scattering-deflecting layer, and the light is scattered while the light enters the scraggly surface of the semiconductor layer, so that the semiconductor light emitting device emits more light.
Another objective of the present invention is to provide a method for manufacturing a semiconductor light emitting device, by forming a semiconductor layer having a scraggly surface, and then forming a light scattering-deflecting layer of which a refractive index is different from that of the semiconductor layer. Thus, after light is deflected by the light scattering-deflecting layer and scattered by the semiconductor layer, the light emitting efficiency of the semiconductor light emitting device can be enhanced.
According to the aforementioned objectives of the present invention, the present invention provides a semiconductor light emitting device comprising: a transparent substrate, wherein the transparent substrate comprises a semiconductor layer formed thereon, and the semiconductor layer comprises a scraggly surface; a light scattering-deflecting layer located on the scraggly surface of the semiconductor layer; and a semiconductor luminescent epitaxial structure located on the light scattering-deflecting layer. A refractive index of the light scattering-deflecting layer is different from that of the semiconductor layer.
According to a preferred embodiment of the present invention, the light scattering-deflecting layer can fill up and level the scraggly surface of the semiconductor layer, or can be conformal with the scraggly surface of the semiconductor layer.
According to the aforementioned objectives of the present invention, the present invention provides a method for manufacturing a semiconductor light emitting device comprising the following steps: providing a transparent substrate, wherein the transparent substrate comprises a semiconductor layer formed thereon, and the semiconductor layer comprises a scraggly surface; forming a light scattering-deflecting layer located on the scraggly surface of the semiconductor layer; and forming a semiconductor luminescent epitaxial structure located on the light scattering-deflecting layer.
According to a preferred embodiment of the present invention, the step of forming the light scattering-deflecting layer is performed by using a metal organic chemical vapor deposition (MOCVD) method to fill up and level the scraggly surface of the semiconductor layer.
The refractive index of the light scattering-deflecting layer is different from that of the semiconductor layer, and the semiconductor layer has a scraggly surface, so that light is deflected and scattered while the light enters the semiconductor layer from the light scattering-deflecting layer. Therefore, the semiconductor light emitting device can emit more light, thus achieving the objective of enhancing the light emitting efficiency.